Flue failure detectors



INVENTORJ filiorn y J L PROUGH ET AL FLUE FAILURE DETECTORS Flled May 121955 Sept. 17, 1957 .I knit 589w Eu r 2,807,013 Patented Sept. 17, 1957FLUE FAILURE DETECTORS James L. Prough and Thomas D. Havlin, Altoona,Pa.

Application May 12, 1955, Serial No. 507,758

4 Claims. (Cl. 340-243) This invention relates to means for detectingflue fail ures and particularly to a device for use in conjunction withautomatically fired furnaces to indicate stoppage or failure of the flueor chimney which might lead to the discharge of carbon monoxide orsimilar noxious gases into the building containing the furnace.

The failure or stoppage of a flue or chimney in connection withautomatically fired furnaces has led to the loss of life by reason ofthe discharge of carbon monoxide into the building in the flue gases.This problem has been recognized for some time and various elforts havebeen made to solve it. Numerous devices have been proposed which dependupon the use of catalytic agents to combine with the noxious gases toactuate an alarm system or otherwise warn of the failure. No simple, nonchemical device for detecting the escape of flue gases has, however,been proposed.

The present invention provides a simple, inexpensive, purely mechanicaldevice for indicating the failure or stoppage of a flue and thedischarge of flue gases. The device of this invention does not dependupon chemical reactions and expensive catalysts.

It is accordingly the principal object of the present invention toprovide a simple, inexpensive mechanical means for detecting fluefailure.

It is another object of this invention to provide a means for detectingflue failures which do not depend for effectiveness upon chemicalreactions or the presence of chemical catalysts.

It is a further object of this invention to provide a structure fordetecting flue failures comprising in combination with a flue diverterhaving an opening to the atmosphere, a low temperature fusable link,means for passing an electrical current through said link and alarmmeans actuated by fusion of said link.

It is another object of this invention to provide a variable fusablelink whose resistance to fusion may be varied.

It is another object of this invention to provide a method of making alow temperature fusable link by compressing a portion of molten lowtemperature fusable material between flat polished surfaces.

Other objects, advantages and purposes of this invention will beapparent from a consideration of the following description and theaccompanying drawings in which:

Figure 1 is an isometric View of a furnace fitted with the flue detectorof this invention.

Figure 2 is a top plan view of one form of this invention partly cutaway.

Figure 3 is a section on the line IilI-II'I of Figure 2.

Figure 4 is a partial top plan view of a second embodiment of thisinvention.

Figures 5 and 6 are sections through polished plates showing the methodof making a fusable link according to this invention.

Figure 7 is a schematic wiring diagram of an alarm circuit according tothis invention.

Figure 8 is a longitudinal section through a variable form of fusablelink according to this invention.

Figure 9 is an end view of the link of Figure 8 view from the right.

Referring to the drawings there is illustrated an automatically firedgas furnace 10 of conventional design provided with a diverter bell 11,a flue pipe 12 and chimney 13. The diverter bell 11 is open at thebottom 14 in the usual manner. All of the foregoing is old and wellknown.

A housing 15 is fixed in the opening 14 of the diverter by means of asemi-flexible sheath 16 and a bracket 17. Openings 18 are provided inthe bottom of the housing 15. A cover 19 is fitted on the housing 15 andis provided with an opening 20 and shield 21 to prevent the entry ofdirt into the housing. A resilient blade conductor member 22 is fixed toan insulator member 23 which is in turn fixed in the interior of thehousing. The conductor member 22 is arranged so as to tend to move intoa position intermediate the cover and the housing, but the free end 22ais held in contact with the housing by a spot of low temperature fusablemetal 24. A pair of conductor members 25 and 26 are brought into thehousing 15 through the sheath 16. One of said conductors 25 is connectedto the resilient blade conductor 22 and the other 26 is connected to thehousing 15, making a complete circuit through conductor 25, blade 22,fusable metal 24, housing 15 and conductor 26. Conductors 25 and 26 areconnected into an alarm circuit such as that shown in Figure 7.

In Figure 7, a transformer 27 is connected to a source of electricalcurrent 28. One of the leads 25 is connected to one side of thetransformer output 29. The other lead 26 is connected to the energizingcoil of a normally closed relay 30 and through the coil to the otherside of the transformer output. A buzzer or bell 31 is connected to thetransformer 27 in a parallel circuit with leads 25 and 26. The normallyclosed relay 30 is placed in the buzzer circuit.

The apparatus of the invention operates as follows: If there is afailure in the flue made up of pipe 12 and chimney 13, the hot fluegases will be diverted through opening 14. The hot gases passing throughopening 14 will enter through openings 18 and 20 into the interior ofhousing 15 and will melt the fusable metal 24. This will release theblade 22 and break the circuit through leads 25, housing 15, blade 22,lead 26 and the coil of relay 30. When the coil of relay 30 isdeenergized, the relay will close to its normal position completing thecircuit through buzzer 31. The buzzer 31 will ring until the circuit isagain broken.

A warning button 32 is preferably fixed on the blade 22 to pass throughan opening 33 in the cover 19 of housing 15. The button 32 is insulatedat '24 from the blade and is preferably colored red to serve as avisible warning of the release of the blade 22 in the event that thebuzzer 31 should fail to give its audible warning.

In an alternative construction as shown in Figure 4, a strip of fusablemetal 35 may be placed within a cylinder of screen wire 36 or similarmaterial through which the hot gases may pass to reach the strip 35. Thestrip 35 is fixed to end caps 37 conducting material which are held inspring clips 38 mounted in housing 39 corresponding to housing 15 ofFigures 2 and 3. Leads 40 and 41 are attached to the clip 39 andcorrespond to leads 25 and 26 of the embodiment of Figures 2 and 3 andare substituted for those leads in making up a circuit similar to thatof Figure 7.

The operation of this embodiment is similar to that of Figures 2 and 3.Hot gases entering the housing 39, pass through screen 36 to strip 35which melts and breaks the circuit through leads 40 and 41.

In Figures 8 and 9 there is illustrated a variable type of fusable linkusable in this invention. A plurality of wires 42 (three in this case)are connected at one end to a cap 43 fixed to a cylinder housing 44through insulators 45. The other ends of the wires 42 are fixed to anend cap 46 which is insulated from housing 44'and rotatable. relativelythereto. Rotation of the cap 46 causes the. wires 42 to be twistedtogether, thereby varyin: their resistance to fusion. Preferably the cap46 is ll him With'the various possible temperature combinations at whichthe wires, 42 can be made to fuse.

In Figures 5 and 6 there is illustrated a method of billing lowtemperature fusable links suitable for use in this invention.Conventional materials are of such m that they do not melt suificientlyrapidly for best resukein this invention. Accordingly a method of mak- 8eulibfaetory material has been developed. A small amunt of molten lowtemperature .fusable material 50 is placed on a polished plate 51 and asecond polished M53 iaihwght. down on the molten material 50 under me.The molten material 50 is then spread out in athiufilm 53 between thetwo plates 51 and .52. This film: 53 is then cut into strips .ofrequired width and thinness.

preferred forms. of the invention have be n illustrated and describedabove it will be understand that this invention may be otherwiseembodied ithin-the scope of the following claims.

We claim: l. A flue failure detector comprising in combination a linediverter having an opening to the atmosphere, a housing adjacent saidopening, a low temperature fusible link in said housing, at least oneaccess opening in the housing facing the opening in the diverter wherebygases leaving the diverter come in contact with the fusible link, meansfor passing an electrical current through said link in series with anormally closed relay held in the open position by current flow throughthe link and alarm means actuated by closing of the normally closedrelay.

2. A flue detector as claimed in claim 1 wherein the position of thehousing facing the opening in the diverter is covered with screen wireacting as a plurality of access openings.

3. A flue failure detector as claimed in claim 1 wherein the fusablelink is made up of a plurality of spaced wires of low temperaturefusable material and means for twisting said wires together intermediatetheir ends whereby their resistance to fusion is altered.

4. A fusable link comprising a housing, a plurality of spaced wires. oflow temperature fusable material extending from two opposite ends of thehousing, and means for twisting said wires together intermediate theirends whereby their resistance to fusion is selectively altered.

References Cited in the file of this patent UNITED STATES PATENTS2,184,983 Tornquist Dec. 26, 1939 2,420,481 Jackson-6t a1. May 13, 19472,496,687 Amprim Feb. 7, 1950 2,682,299 Field June 29, 1954 FOREIGNPATENTS,

110,033 Australia Mar. 6, 1940

